Effect of hyperprolactinemia on luteinizing hormone and prolactin secretion assessed using the reverse hemolytic plaque assay

M. A. Sortino, P. M. Wise

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Hyperprolactinemia (hyperPRL) frequently suppresses luteinizing hormone (LH) and endogenous rat prolactin (rPRL) secretion under a variety of experimental circumstances. Several lines of evidence suggest that elevated prolactin (PRL) may act at the hypothalamic-pituitary axis to inhibit pituitary hormone secretion. The goal of this study was to determine whether hyperPRL, achieved by administration of ovine PRL (oPRL), influences LH and rPRL secretion as assessed by the reverse hemolytic plaque assay. Young Sprague-Dawley rats were ovariectomized on Day 0 and were treated with oPRL (4 mg/kg body weight, 3 times/day) beginning at 0900 h on Day 4. They were killed at 1000 h on Day 6, anterior pituitaries were collected, and cells were dispersed for the reverse hemolytic plaque assay. We analyzed mean plaque area by using a computerized image analysis system and determined the percentage of plaque-forming cells by counting the number of plaques compared to the total number of cells. HyperPRL decreases the percentage of LH plaque-forming cells under basal conditions. Although the mean LH plaque area was the same in vehicle-treated and oPRL-treated rats under basal and gonadotropin-releasing hormone-stimulated conditions, hyperPRL altered the frequency distribution of different-sized plaques under basal conditions. It appears that hyperPRL shifts the distribution of different-sized plaques such that there are more small plaques and no plaques of the largest size classes. Basal and thyrotropin-releasing hormone-induced rPRL release from single lactotropes, as measured by mean plaque area and the percentage of plaque-forming cells, is lower in lactotropes from hyperPRL rats than in controls after 1 h, but not 2 h, of incubation. HyperPRL alters the frequency distribution of different-sized plaques after both 1 h and 2 h of secretion. These data suggest that hyperPRL suppresses LH and rPRL secretion by several mechanisms. In the case of its effect on gonadotropes, hyperPRL appears to decrease LH secretion primarily by decreasing the proportion of pituitary cells that secrete LH, whereas in the case of its effect on lactotropes, hyperPRL influences the secretion per cell and its responsiveness to secretagogues.

    Original languageEnglish (US)
    Pages (from-to)618-625
    Number of pages8
    JournalBiology of reproduction
    Volume41
    Issue number4
    DOIs
    StatePublished - 1989

    ASJC Scopus subject areas

    • Reproductive Medicine
    • Cell Biology

    Fingerprint Dive into the research topics of 'Effect of hyperprolactinemia on luteinizing hormone and prolactin secretion assessed using the reverse hemolytic plaque assay'. Together they form a unique fingerprint.

    Cite this